This disclosure is directed to stabilizers for pigments in solid inks. More specifically, this disclosure is directed to five member ring stabilizers for quinacridone-type pigments in solid inks.
Inkjet printing systems and solid inks are known in the art. However, while known solid ink compositions are used successfully, a need remains for improved dispersion of pigments in solid inks.
To enable dispersion of the pigments in media, a dispersant or combination of dispersants may optionally be provided. Typically, dispersants may be used to stabilize particles in a non-polar ink vehicle. The dispersant generally comprises first functional groups that anchor the dispersant to the pigment particles and second functional groups that are compatible with the ink vehicle. The first functional groups can suitably anchor or adsorb to the pigment particle in any suitable manner, such as hydrogen bonding, chemical bonding, acid-base reaction, Van der Waals interactions, and the like.
However, many organic pigments disperse with difficulty in non-polar media. One approach for dispersing pigments into non-polar media is by modifying the surface of the pigments by addition of compounds known as synergists. A pigment stabilizer or synergist works by enhancing the attachment of the dispersant onto the pigment. Therefore, it is desirable for the stabilizer to have the same basic chemical structure as the pigment, but substituted by a functional group, such as a sulfonic acid group.
However, obtaining stabilizers for use in solid ink compositions has not been fully explored, and there remains a need to develop stabilizers for organic pigments, particularly quinacridone-type pigments, for use in non-polar solid ink compositions.